如何检测UIImageView上的触摸并绘制线条？

我已经创建了一个ViewController，并在自定义类中选择了myView。在myView中，当用户单击并拖动手指时，它将绘制一条直线，当它再次拖动时，前一行消失，并创建新的一条。如何检测UIImageView上的触摸并绘制线条？

我的代码：

@implementation GestureView 

{ 
    CGPoint _originOfTouchPoint; // your fist touch detected in touchesBegan: method 
    CGPoint _currentFingerPositionPoint; // the position you have dragged your finger to 
    CGFloat _strokeWidth; // the width of the line you wish to draw 
    id _touchStartedObject; // the object(UIView) that the first touch was detected on 
} 

// If you use Interface Builder to design your interface, Objects in a nib file are reconstituted and then initialized using 
// their initWithCoder: method 
- (id)initWithCoder:(NSCoder *)decoder 
{ 
    self = [super initWithCoder:decoder]; 
    if (self) { 
     // Initialization code 
     _originOfTouchPoint = CGPointMake(0.0, 0.0); 
     _currentFingerPositionPoint = CGPointMake(100.0, 100.0); 
     _strokeWidth = 2.0; 
    } 
    return self; 
} 
/* 
// Use initWithFrame if you are not loding the UIView from a nib file 
- (id)initWithFrame:(CGRect)frame 
{ 
self = [super initWithFrame:frame]; 
if (self) { 
// Initialization code 
_originOfTouchPoint = CGPointMake(0.0, 0.0); 
_currentFingerPositionPoint = CGPointMake(100.0, 100.0); 
_strokeWidth = 2.0; 
} 
return self; 
} 
*/ 

// Only override drawRect: if you perform custom drawing. 
// An empty implementation adversely affects performance during animation. 
- (void)drawRect:(CGRect)rect 
{ 
    CGContextRef context = UIGraphicsGetCurrentContext(); 
    CGContextSetStrokeColorWithColor(context, [UIColor blueColor].CGColor); 
    CGContextSetLineWidth(context, _strokeWidth); 
    // fisrt point of line 
    CGContextMoveToPoint(context, _originOfTouchPoint.x, _originOfTouchPoint.y); 
    // last point of line 
    CGContextAddLineToPoint(context, _currentFingerPositionPoint.x, _currentFingerPositionPoint.y); 
    // draw the line 
    CGContextStrokePath(context); 
} 

#pragma mark touches 

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event 
{ 
    // get starting point and first view touched (if you need to send that view messages) 
    _originOfTouchPoint = [[touches anyObject] locationInView:self]; 
    _touchStartedObject = [[touches anyObject] view]; 
} 
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event 
{ 
    CGPoint movedToPoint = [[touches anyObject] locationInView:self]; 
    // if moved to a new point redraw the line 
    if (CGPointEqualToPoint(movedToPoint, _currentFingerPositionPoint) == NO) 
    { 
     _currentFingerPositionPoint = movedToPoint; 
     // calls drawRect: method to show updated line 
     [self setNeedsDisplay]; 
    } 
} 
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event 
{ 
    // reset values 
    _originOfTouchPoint = CGPointZero; 
    _currentFingerPositionPoint = CGPointZero; 
    _touchStartedObject = nil; 
} 

@end

我已经添加上的ViewController 3 ImageView的，我想检测触摸时，在任何ImageView的用户点击，然后当他拖动他的手指该行开始从ImageView的绘制。我可以在任何地方画线在屏幕上，但我想限制当点击的ImageView并在另一个ImageView的结束

enter image description here

来源

2013-03-19 Zohaib

参考里面的链接代码https://github.com/GrioSF/Android-Pattern -Lock-on-iOS – Tirth 2013-03-19 10:30:59

您必须修改[touches anyObject]，使用您的uiimageview对象更改anyObject – 2013-03-19 10:35:16

您可以在默认情况下它的启用与-[UIView setUserInteractionEnabled:]触摸只是画线NO对UIImageView

关于绘画...从文档：

UIImageView类经过优化，可将其图像绘制到显示屏上。 UIImageView不会调用drawRect：一个子类。如果您的子类需要自定义绘图代码，建议您使用UIView作为基类类。

来源

2013-03-19 10:32:51 RolandasR

试试这个：

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event 
{ 
    UITouch *touch = [touches anyObject]; 
    //To get tag of touch view 
    int viewTag=[touch view].tag; 

    if ([[touch view] isKindOfClass:[UIImageView class]]) 
    { 
     //Write your code... 
    } 
}

，并设置所有触摸图像UserInteractionEnabled这样的：

[imageName setUserInteractionEnabled:YES];

来源

2013-03-19 13:54:05

如何检测UIImageView上的触摸并绘制线条？

回答

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